For multipurpose thermoplastics such as ABS resin, polycarbonate resin, polyester resin, polystyrene, and acrylic resin, it has been known how to improve impact resistance, weather resistance, pigment coloringability, and pyrolysis resistance.
For example, JP-B-4-325542 describes a method of improving appearance of a product without deterioration of the impact resistance by adding specific alcohol to a rubber polymer latex. JP-A-10-101869 describes a method of improving impact resistance of the multipurpose thermoplastics by adding graft copolymers obtained by graft polymerization of vinyl monomers to composite rubbers having inseparable structures comprising isobutylene polymer segments and vinyl polymer segments.
There is a method of improving impact resistance of the thermoplastic by adding a resin as a modifier obtained by graft polymerization of methyl methacrylate, styrene, acrylonytrile, and the like to butadiene rubber polymer, for example, MBS (Methylmethacrylate-Butadiene-Styrene) resin and the like. However, the weather resistance tends to be reduced when the MBS resin is added, and the impact resistance tends to be reduced rapidly as time passes when a molded article made of the thermoplastic containing it is used outdoors. It is considered that one of the major causes of the deterioration of the weather resistance is due to degradations of butadiene units in the MBS resin by ultraviolet light.
JP-B-51-28117 describes a method of improving the weather resistance and the impact resistance by using a graft copolymers obtained by graft polymerization of methyl methacrylate, styrene, acrylonytrile, and the like to crosslinked alkyl (meth) acrylate rubber polymer obtained by alkyl (meth) acrylate monomers and crosslinking agents. However, the coloringability such as the pigment coloringability of the graft polymer tends to be lower than that of the MBS resin due to refractive indexes of acrylic resins and so on.
JP-A-2001-31830 describes a thermoplastic resin composition having improved coloringability, weather resistance, and impact strength by controlling particle diameter of polymer. Especially, it is described that color of the composition tends to be improved when rubber particle diameter of an impact modifier becomes smaller and MBS resin may be added to also improve the impact resistance. However, the polymer isn't used for matrix resin.
JP-A-2000-26552 describes an impact modifier using original acrylic composite rubber, and JP-A-2000-319482 describes an impact modifier using acrylic composite rubber having specific particle diameter distribution. These modifiers can improve the impact resistance. However, these don't describe general material properties especially required for engineering plastics such as coloringability which affects appearance and recyclingability. And, at present, demanded properties are higher than those of the modifiers.
As for the method of providing balanced weather resistance, coloringability, and impact resistance on high levels, there is ample scope for improvement when prior arts are adopted. For example, to skip coating of housing material for automobile or OA equipment, a method of providing balanced coloringability, especially ebonyty in dark colors impact resistance, and weather resistance on high levels at the same time is one of the most demanded technologies at present.